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Questions tagged [falcon-9]

Questions regarding the Falcon launch vehicle developed by SpaceX for medium payloads (15,000 lbs) to LEO and GEO (via GTO, second stage cannot inject into GEO direct)

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Why is the water pumped out of the holding tank a minute before Falcon 9 liftoff?

SpaceX Falcon 9 - starlink mission on October 5. Video : Why is the water discharged at T- 01m:30s from the holding tank far away from the launch pad? This was also ...
Ashvin's user avatar
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9 votes
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Do the second stages for Starlink launches from Florida do a deorbit burn over Texas?

This article about "strange red glows over Texas" claims that for Starlink launches from Florida, the second stages do a deorbit burn over Texas resulting in a South Atlantic Ocean impact. ...
Organic Marble's user avatar
9 votes
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Roughly how many self-viewing cameras are present in a Falcon 9 LEO mission?

Watch any of last year's SpaceX LEO satellite deployment missions's broadcasts in YouTube, and you can see views from at least several different cameras. At least two on the 2nd stage nozzle, at least ...
uhoh's user avatar
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8 votes
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635 views

How is retropropulsion by the Falcon 9 first stage being used to design retropropulsion entry on Mars?

Much has been made of how the reentry burns of Falcon 9 first stages occur at an altitude where the atmosphere is similar in density to the atmosphere of Mars, and so they demonstrate that supersonic ...
kim holder's user avatar
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7 votes
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Crew Dragon: How thick is the skin?

Auto body panels are about 20-gauge, or just under 1 mm thick. This is fine for many reasons: thin panels are light for good fuel economy and crumple easily for shock absorption without unnecessary ...
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7 votes
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581 views

What would be the range safety for vertically landing over land rockets?

sideFrom the Wikipedia article on range safety: Rockets are usually launched into a space above the launch range called the launch corridor. If rocket engines fail while the rocket flies inside ...
Val's user avatar
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6 votes
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Bumps/nodes on rocket skin: What are they?

I've wondered for a while now what the many bumps and nodes on a rocket's skin are. Picture below for example (red lines mark bumps). Can someone clarify?
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SpaceX Dragon Shape: Power Series, Ellipsoid, or Haack/Von Karman?

The SpaceX Dragon module has a round apex typical of power series, ellipsoid, and Haack/Von Karman shapes. I'm wondering which of these SpaceX actually used. References would be appreciated. My guess ...
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321 views

What (the heck) is this purple donut in the video of the Falcon 9 fairing's atmospheric reentry?

This SpaceX tweet (found in CNET's SpaceX camera captures incredible view of rocket part returning to Earth) shows a video taken by a camera in one half of the fairing on the recent STP-2 mission and ...
uhoh's user avatar
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6 votes
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165 views

What accounts for the signal delay from cameras on the Falcon 9?

On the last few webcasts, SpaceX has shown video from both ground tracking cameras and the on-board camera side-by-side, and there's a noticable delay between the two, with the on-board camera being ...
John Bode's user avatar
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6 votes
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How long does it take to chill the LOX and RP1 for Falcon 9 V1.1 Full Thrust?

The new version of the Falcon 9 v1.1 Full Thrust, or as SpaceX would like everyone to start calling it "Falcon 9", uses super cooled LOX and RP1 to improve the density of the fuel for better ...
geoffc's user avatar
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6 votes
1 answer
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How does the flight trajectory of a GEO vs LEO mission vary for a Falcon 9 first stage?

How does the trajectory vary between the two types of missions? Specifically, how does the speed and velocity vary for the booster for a Falcon 9 mission?
PearsonArtPhoto's user avatar
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5 votes
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How large is the AoA during the ascent and descent of a Falcon 9?

If we divide the mission into ascent, descent before reentry burn, and descent after that, how large is the AoA (Angle of Attack) in each of these three phases? Is there any difference between the ...
جامکلو حسن's user avatar
5 votes
2 answers
483 views

Crew Dragon: Could launch escape thrust determine payload capacity?

The superdracos in Dragon's launch escape system each produce $\color{black}{\texttt{71.2 kN}}$ (16,000 lbf) of thrust. There are eight superdracos, giving a combined thrust of $\color{black}{\texttt{...
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5 votes
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121 views

Electrical power requirements for Starship or Falcon 9

Anybody know where one could dig up electrical requirements for Starship? In other words, if Starship were sitting on the launch pad drawing power prior to launch, what would the load be? I imagine ...
ijnabe47's user avatar
5 votes
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142 views

In landing, how much of a Falcon 9 First stage's velocity is lost to air resistance and how much to retropropulsion?

Thinking about this question I was led to wonder to what extent retropropulsion is used to kill the F9 first stage's full velocity and to what extent it is used simply for course control and landing, ...
Steve Linton's user avatar
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Does the downrange position of an ASDS vary, depending on payload mass?

SpaceX in its recovery attempts can either do a Return To Launch Site (RTLS) or land downrange on an ASDS landing barge. The Telesat 19V and 18V payloads were some of the heaviest payloads on the ...
geoffc's user avatar
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5 votes
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972 views

Dragon 2 in-flight abort test - what will happen to the booster?

SpaceX is planning to do an in-flight abort test of the Dragon 2. I imagine that at max-Q the Dragon will start its own motors to fly slightly faster than the booster (and move sideways). Suddenly ...
filo's user avatar
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5 votes
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SpaceX CRS-11 landing pad debris identification

After sending CRS-11 into orbit to rendezvous with the space station, the first stage of the SpaceX rocket Dragon landed on Landing Zone one. In the video released subsequently you can see two pieces ...
Adam Davis's user avatar
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Will the International Space Station be able to see the Falcon 9 (Inspiration4 launch)

Will astronauts aboard the International Space Station be able to see any part of the Inspiration4 flight of the Falcon 9 during launch and/or during orbit?
RICK's user avatar
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How does a returning Falcon first stage decide when to end its re-entry burn?

When a Falcon 9 first stage is returning to Earth to land, it performs a brief re-entry burn in order to slow down. My question is, what criteria does the first stage control software use to decide ...
Jeremy Friesner's user avatar
4 votes
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300 views

Falcon 9 cold gas thrusters: why in line with grid fins?

The cold gas thrusters of the Falcon 9 are right in line with the grid fins. The grid fins deploy immediately after MECO and stay deployed while the cold gas thrusters fire. And it seems the expelled ...
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4 votes
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345 views

How soon after launch is pitchover done?

I'm reading conflicting things on the timing of the pitchover. When exactly does it start? Many people write that it's almost immediately after launch, as soon as it's practical. Once the rocket ...
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4 votes
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47 views

What does diiferent colours in orbital path seen in the CRS 21 launch video indicate?

The SpaceX broadcast of Falcon 9 - CRS 21 launch showed the orbital path of the vehicle differently than previous videos. Separate green lines and rectangualar boxes were visible. What additional ...
Ashvin's user avatar
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4 votes
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2k views

How do Falcon-9's cold gas thruster maneuvers account for the center of mass changes due to "floating fuel shifts"?

The Art of Engineering video How SpaceX Lands Rockets with Astonishing Accuracy after 07:19 explains: Cold Gas Thrusters The falcon 9 is equipped with a total of ...
uhoh's user avatar
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4 votes
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202 views

how much force can a falcon 9 landing leg handle

According to spacex, the falcon 9 landing legs are made of carbon fiber with aluminum in a honeycomb shape. How much force would be needed to break that?
cf68916's user avatar
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What happens between Payload deployment and the ISS docking

When SpaceX is livestreaming their CRS missions they usually end up by separating the payload from the second stage with an altitude at about 200 km. But I am wondering how the payload gets up to the ...
rehti's user avatar
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4 votes
0 answers
351 views

Books on Vertical-Landing Vertical-Takeoff (VTVL) of Rockets? or Rocket Design in General?

I am working on a rocket control system design and I am trying to understand the the fundamental principles and concepts to design an efficient controller for recovering and landing the rocket, ...
John's user avatar
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4 votes
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685 views

Falcon 9 Landing Speed

I wanted to know what the fastest speed is that a Falcon 9 can land at and thus the max force the landing legs can withstand. I assumed the mass when landed is 26,000 kg (I once heard that somewhere). ...
Philip Waldman's user avatar
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192 views

Is there any flutter analysis available regarding Falcon's grid fins?

I have never come across any papers which talks about flutter analysis of gridded fins in general, does it not under go flutter behavior or is it technically incorrect to talk about flutter for ...
ashcoolaero's user avatar
4 votes
0 answers
102 views

How long does it take SpaceX to mount a stage on the McGrgeor test stand, run the test, and dismount it?

Gwynne Shotwell at SmallSat 2016 in Utah mentioned that SpaceX would be using the JCSAT-14 recovered first stage as a fleet leader in wear and tear. That they would be mounting it on the McGregor, TX ...
geoffc's user avatar
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4 votes
0 answers
622 views

Falcon 9 v1.1 Full Thrust Specifications

Does anyone know what the dry mass and mass ratio of the Falcon 9v1.1 Full Thrust Stage 1 is? The best info I've been able to find was by taking the specified burn time and multiplying it by the mass ...
sevenperforce's user avatar
4 votes
1 answer
247 views

Why does SpaceX Crew Dragon not have planned holds?

I watched the launches of SpaceX Crew Demo 2 and Crew 1. I observed that there were no planned holds during the last hour of the countdown. The Space Shuttle had planned holds at T-20 minutes and T-9 ...
Codes with Hammer's user avatar
3 votes
0 answers
236 views

What advantages will Rocket Lab's Neutron have over the Falcon 9?

With Neutron's debut coming up next year, are there any advantages of Rocket Labs design over SpaceX's Falcon 9 FT? The most obvious I can see are the attached fairings, but certainly with all the ...
David's user avatar
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3 votes
0 answers
66 views

Recent GPS III Launch Intended or Unplanned Venting?

Between 14:01 and 14:14 in the following video, there is a significant gas vent happening behind the engine bell: Is this working as intended, or does that appear to ...
HumanJHawkins's user avatar
3 votes
0 answers
144 views

Falcon 9: transonic attitude control on reentry

Attitude control on the falcon 9 is done with engine thrust vectoring, cold gas thrusters, and grid fins. After the reentry burn, when the rocket stage is in the atmosphere, there is a short period ...
user avatar
3 votes
0 answers
209 views

Why do Falcon 9 grid fins open in piecemeal fashion?

The grid fins on Falcon 9 seem to open in piecemeal fashion: extending a few degrees, pausing, extending a few degrees, pausing, etc. Any reason why this happens? The rocket stage is around 80 km high,...
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3 votes
0 answers
72 views

Falcon 9 Flipover Direction?

Consider a Falcon 9 at MECO. The rocket's close to 30 deg relative to the local horizon, down from the 90 deg it had at launch. Stage 1 separates and flips more or less 180 degrees for the return ...
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3 votes
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273 views

What is the inlet and outlet pressure of Merlin LOX/RP-1 turbopump?

I got the inlet and outlet pressure of Saturn V engines turbopumps here, but I couldn't find the turbopump pressure of the Merlin engine of Falcon 9.
Hello Humans's user avatar
3 votes
0 answers
172 views

What are the protrusions on the outside of the Falcon 9 nose fairing?

Near the base of the Falcon 9 nose fairing is an array of square protrusions (marked in red) that you'd probably want to avoid unless they serve a very essential purpose. Does anyone know what that ...
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3 votes
0 answers
75 views

Altitude at which Falcon boosters go subsonic during reentry

Is there a distinct altitude at which Falcon boosters goes subsonic during reentry? If so, which is it? Is it +/- the same altitude for every flight?
George Knap's user avatar
3 votes
0 answers
221 views

Where will the DSCOVR mission Falcon 9 2nd stage rocket body end up?

This answer to Why would a mission to Sun-Earth L1 have an instantaneous launch window? suggests that this was quite a delta-v-intensive launch. It left the F9 2nd stage in a very high 17 day orbit ...
uhoh's user avatar
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3 votes
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149 views

Space-X Falcon-9 and Falcon Heavy fuel consumed for landing

The question is, how much fuel is used by each of above rockets for landing (in % of whole fuel of the rocket) as a function of three following components - payload, orbit and descend trajectory (land/...
kreuzerkrieg's user avatar
3 votes
0 answers
94 views

Where are Falcon 9 1st stage GN2 tanks located?

Is nitrogen propellant for the two cold gas thrusters pods contained in the interstage? The view we have from the B5-B1050 recovery shows several small COPV(s) pic1 Here you can see where the cold gas ...
redshiftseven's user avatar
3 votes
0 answers
95 views

What became of slowing down and recovering the falcon 9 upper stage using large balloons

On 16 April 2018, Elon Musk posted on twitter This is gonna sound crazy, but … SpaceX will try to bring rocket upper stage back from orbital velocity using a giant party balloon And then land on a ...
Speedphoenix's user avatar
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3 votes
0 answers
299 views

Is the outside surface temperature of a Falcon 9 below freezing? How is the LOX insulated?

This answer explains how the liquid oxygen in a Falcon 9 is evaporation cooled to maintain a temperature well below boiling, by bubbling helium through it. The temperature difference to the ...
Peter - Reinstate Monica's user avatar
3 votes
0 answers
122 views

How much do SpaceX's titanium grid fin geometrical parameters measure?

Does anyone know approximately what is the width, length, thickness and depth of the titanium grid fins used in the Falcon9 v1.1? I'm trying to make a 3D model on solidworks but can't find the ...
Gerard's user avatar
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3 votes
0 answers
328 views

What is the function of this Merlin engine's tube, and why is it getting red hot?

In the video of the recent SpaceX Starlink launch, one view of the Falcon-9 2nd stage engine shows a cane-shaped tube that glows red hot at the "handle" end and seems to get hotter over time....
uhoh's user avatar
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3 votes
0 answers
468 views

Are these two length scales in FH exhaust plumes real, understood, and distinct?

The Ars Technica article We can admit it—we’re dazzled by the controlled fury of the Falcon Heavy includes a beautiful photo of the exhaust plume produced by the 27 engines of a Falcon Heavy launch. ...
uhoh's user avatar
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3 votes
0 answers
323 views

How much helium and nitrogen are used in SpaceX's Falcon 9?

How much helium and nitrogen are used on SpaceX's Falcon 9?
daveb's user avatar
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